LMWQCC is a 450,000 EP facility that treats sewage from the majority of the nation’s capital. ASpect undertook the process design component of the $56M secondary treatment augmentation in 2006. The amplification was fully commissioned by late 2010. A severe wet weather event in late 2010, and a further event in early 2012 tested the capacity and performance of the facility. ACTEW wanted to learn as much as they could from these events and extrapolate this to fine tune to long term strategy for the plant. ASpect used post commissioning data to tightly calibrate a full plant process model that was then used to test scenarios. These model predictions were tested and further calibrated against the wet weather events. ASpect was able to show that the actual capacity of the facility was greater than the design capacity, largely due to inventory shifts from the reactos to the clarifiers. This prolonging the life of the facility and postponing further planned augmentation. ASpect also analysed the capacity effects of possble tightening of load limits on total nitrogen (TN), avenues for further process optimisation and where to focus trials that could reduce future investment.